Pharmacology/Toxicology Case Studies

134 Pages·2016·0.86 MB·English

Pharmacology/Toxicology
Case Studies

+ 132 Pages
+ 60 Case Studies
+ Each case includes
multiple questions
followed by a detailed
explanation
Acknowledgments

Ohio Chapter ACEP would like to thank the following for their invaluable
contributions to this text:

Text and Editor: Hannah L. Hays, MD

Reviewers: Marcel J. Casavant, MD, FACEP, FACMT
Kristin Daugherty, MD
Heath Joliff, DO, FACEP

Copyright © 2012, 2006, 2000, 1997
Ohio Chapter, American College of Emergency Physicians. All rights
reserved. No part of this publication may be reproduced or transmitted in
any form, electronic or mechanical, including photocopying, recording,
storage in any information retrieval system, or otherwise, without written
permission from the publisher.

Ohio Chapter, American College of Emergency Physicians
3510 Snouffer Road, Suite 100, Columbus, Ohio 43235
[phone]
(888) OHACEP4 (642-2374)

[email protected]
www.ohacep.org
PHARMACOLOGY/TOXICOLOGY CASE STUDY #1

History: A 14-year-old female is brought to your emergency department by her
parents after she admitted to ingesting a total of ten, 250 milligram
amoxicillin tablets four hours ago after an argument at home that resulted
in loss of her phone privileges. Her parents are concerned that she was
trying to kill herself. She denies any co-ingestion and has no symptoms.
There are no other prescription medications in the home.

PMH: None.

Physical Examination:
T: 99°F HR: 100 bpm RR: 16 breaths per minute BP: 100/70 mm Hg
General: The patient is tearful, but otherwise in no distress.
The remainder of the physical exam is completely normal.

QUESTIONS CASE STUDY #4

1. What testing, if any, should be obtained?

2. Should activated charcoal be administered?

3. Are there other treatments that should be considered?
[1]
© Ohio Chapter, American College of Emergency Physicians
www.ohacep.org
CASE STUDY #1: GENERAL APPROACH TO TOXIC INGESTIONS

1. Acetaminophen levels should be obtained in all cases of reported or suspected
poisoning, regardless of history and physical exam. Acetaminophen is readily
available and patients can initially present without signs or symptoms even with
toxic levels. Dose history should not be used to make management decisions
because studies have found no correlation between the amount of
acetaminophen reportedly ingested and the serum concentration measured. The
patient’s four hour acetaminophen level in this patient was 85 ug/mL. A
pregnancy test should be performed in all females of childbearing age, as women
may attempt suicide due to an unwanted pregnancy.

The role of routine urine drug screening in the evaluation of patients presenting
to the emergency department with psychiatric-related complaints is controversial.
ACEP’s Clinical Policy: Critical Issues in the Diagnosis and Management of the
Adult Psychiatric Patient in the Emergency Department, published in January
2006, makes a level C recommendation that routine urine screening for drugs of
abuse in alert, awake, cooperative patients does not affect ED management and
need not be performed as part of the ED assessment. Often, this testing is
requested by the receiving psychiatric facility for admission purposes, long-term
care planning or diagnosis. In these cases, it may be reasonable to obtain this
testing in the emergency department; however this testing should not delay
patient evaluation or transfer. These recommendations relate to the management
of adult psychiatric patients; pediatric patients are excluded.

2. Previously, activated charcoal was not routinely recommended in treatment of
ingestions that occurred greater than one hour prior to presentation; however
newer data regarding acetaminophen ingestions suggests that the half-life of this
drug in the stomach is markedly increased in overdose settings and that there
may be some therapeutic benefit to its administration past the traditional one
hour mark. Other circumstances that may warrant charcoal administration past
the one hour mark include massive overdoses, poisoning with sustained release
preparations and ingestion of agents that slow gastrointestinal motility. or
acetaminophen, activated charcoal may offer some benefit when used up to four
hours post ingestion.

3. The patient does not require treatment with N-acetylcysteine because her four
hour acetaminophen level falls below the toxicity line on the Rumack-Matthew
nomogram. Based on recommendations from the American Academy of Clinical
Toxicology, this patient does not meet criteria for gastric lavage as she meets
neither of two criteria for this intervention: ingestion of a potentially life-
threatening amount of a poison and presentation within 60 minutes of ingestion.
For similar reasons, this patient will not benefit from whole bowel irrigation. Home
administration of ipecac syrup is no longer recommended by the American
Academy of Pediatrics and its routine use in the emergency department is
discouraged by the American Academy of Clinical Toxicology.
[2]
© Ohio Chapter, American College of Emergency Physicians
www.ohacep.org
PHARMACOLOGY/TOXICOLOGY CASE STUDY #2

History: A 40-year-old male presents to your emergency department after falling
into a vat of chromic acid. The patient arrives via EMS with a dry cough
and is actively vomiting. He is complaining of chest pain and shortness of
breath.

PMH: Asthma.
Medications: Albuterol inhaler as needed.

Physical Examination:
T: 98.6°F HR: 115 bpm RR: 29 breaths per minute BP: 176/94 mm Hg
General: He is awake and alert.
HEENT: Normal.
Pulmonary: Diffuse wheezing, poor air exchange.
CV: Tachycardic, regular rhythm without murmur, normal perfusion.
Extremities: Diffuse skin ulcers in exposed areas.

QUESTIONS CASE STUDY #2

1. What would be your initial approach to this patient?

2 What complications may be associated with this type of exposure?

3. What therapy is indicated?
[3]
© Ohio Chapter, American College of Emergency Physicians
www.ohacep.org
CASE STUDY #2: CHROMIC ACID EXPOSURE

1. Decontamination should accompany stabilization of the airway, breathing and
circulation. The patient should have all clothing removed and copious aqueous
irrigation performed.

2. Chromic acid is a strong acid that contains the hexavalent (CrVI3), or most
hazardous, form of chromium. Acute skin exposure may cause burns and chronic
exposure may result in skin and nasal ulcer formation. These skin ulcers are
round or oval growths with reddish edges and necrotic centers and are often
referred to as “chrome holes” or “chrome sores”. Chromic acid inhalation may be
associated with upper respiratory irritation and bronchospasm, manifested by
cough, chest pain and dyspnea. Pulmonary congestion visible on radiographs,
interstitial pneumonia and delayed, non-cardiogenic edema have been reported.
Systemic effects include renal failure secondary to acute renal tubular acidosis,
hemolysis and liver damage.

3. Initially, the focus should be decontamination, including removal of contaminated
clothing and a deluge, or heavy downpour safety shower. Fluid and electrolyte
balance should be maintained, especially in the case of large skin and mucosal
lesions which can lead to significant fluid losses. The efficacy of activated
charcoal has not been demonstrated. Ascorbic acid (vitamin C) has been
recommended for cases of ingestion and skin exposure to reduce absorption of
chromium by oxidizing it from the hexavalent to trivalent form, which does not
cross cell membranes as rapidly. This intervention must be performed within two
hours of exposure. Beta agonist therapy is indicated for bronchospasm. Patients
should be observed for the development of renal failure, non-cardiogenic
pulmonary edema and liver failure. Hemodialysis, exchange transfusion and
chelation therapy are ineffective.

The Poison Control Center should be called for advice on antidotes and for
assistance with management of poisoning/exposure to unfamiliar chemicals.

Prevention of exposure to chromium, particularly respiratory exposure, is critical
as chromium has a demonstrated carcinogenic potential.

[4]
© Ohio Chapter, American College of Emergency Physicians
www.ohacep.org
PHARMACOLOGY/TOXICOLOGY CASE STUDY #3

History: A 30-year-old white male presents to your emergency department after
ingesting “white powder” from a bag that was given to him by his friend.
He has developed weakness, vomiting and diarrhea.

PMH: None.

Physical Examination:
T: 100.4°F HR: 120 bpm RR: 20 breaths per minute BP: 90/60 mm Hg
General: He is awake and alert, but actively vomiting and having diarrhea.
Pulmonary: Clear to auscultation.
CV: Tachycardic without murmur, normal perfusion.
Neurologic: GCS 15. Cranial nerves II-XII intact. Remaining neurologic exam is
nonfocal.

QUESTIONS CASE STUDY #3

1. From what type of poisoning is this patient suffering and what are the typical
signs and symptoms?

2. What initial therapy, if any, should be instituted?
[5]
© Ohio Chapter, American College of Emergency Physicians
www.ohacep.org
CASE STUDY #3: ARSENIC POISONING

1. This patient is suffering from arsenic poisoning. Arsenic is a naturally occurring
metalloid element. Acute poisoning predominantly affects the gastrointestinal
system, causing nausea, vomiting, abdominal pain and diarrhea. Affected
individuals may have a garlic odor to their breath or stool. Resultant dehydration
heralds cardiovascular instability, which occurs rapidly and progresses from
sinus tachycardia to orthostatic hypotension with possible shock and death,
depending on the amount and form of arsenic ingested. Patients may develop
severe encephalopathy with delirium, confusion, seizures and coma. Other acute
complications include rhabdomyolysis and acute renal failure.

Although a symmetrical sensorimotor peripheral polyneuropathy may develop 1-3
weeks following ingestion, some patients may develop symptoms within 24
hours. Sensory symptoms usually occur first with patients complaining of “pins
and needles” or electrical shock-like pains in the lower extremities. Early
examination may demonstrate isolated, diminished or absent vibratory sense.
Motor weakness may later develop and can sometimes mimic Guillain-Barré
syndrome. Reversible pancytopenia and hepatitis can occur within one week
after the initial illness. Dermatologic lesions, a dry, hacking cough and Mees lines
(horizontal 1-2 mm white lines on the nails) can also develop after severe acute
and chronic exposures.

2. The white powder was rapidly identified as arsenic and a spot urine arsenic level
was sent for confirmation of ingestion. Blood and urine were sent to the lab
for determination of arsenic levels. Acute arsenic toxicity is life threatening and
necessitates aggressive treatment.

Initial management should be focused on stabilizing the airway, breathing and
circulation. The patient should receive 2 large bore IV’s and be placed on a
cardiac monitor with continuous pulse oximetry. Hypotension should be treated
with crystalloid fluids; however, pressor agents may be required. Fluid status
should be carefully monitored, as cerebral and pulmonary edema may occur.
Potassium, calcium and magnesium concentrations should be maintained in the
normal range and urine output should be maintained. Ventricular dysrhythmias
may occur. Ventricular tachycardia and ventricular fibrillation are treated with
lidocaine and electrical defibrillation. Because arsenic is associated with
prolongation of the QTc, agents that prolong the QTc should be avoided (class
IA, IC and III antidysrhythmic agents). Bicarbonate therapy may be effective.

Chelation therapy should be initiated as soon as possible with Unithiol (DMPS, a
water-soluble analog of dimercaperol), dimercaperol (BAL, second choice if
unithiol not immediately available) or DMSA (oral succimer), under the direction
of a medical toxicologist.

Activated charcoal is sometimes used for ingestions that present within one hour,
but its efficacy has not been proven.
[6]
© Ohio Chapter, American College of Emergency Physicians
www.ohacep.org
PHARMACOLOGY/TOXICOLOGY CASE STUDY #4

History: A 12-month-old male presents to your emergency department after
ingesting a watch battery, which was left out on the counter. He has been
drooling since the incident and refusing his bottle.

PMH: None.

Physical Examination:
T: 98.6°F HR: 137 bpm RR: 32 breaths per minute BP: 100/62 mm Hg
General: He is awake, alert and calm in appearance.
HEENT: Drooling from mouth.
Pulmonary: Clear to auscultation.
CV: Regular rate and rhythm without murmur, normal perfusion.
Extremities: Normal.

QUESTIONS CASE STUDY #1

1. What is the initial approach to this patient?

2. What complications may be associated with these types of batteries?

3. On x-ray, the battery is located in the esophagus at the level of the aortic arch.
What therapy is indicated?
[7]
© Ohio Chapter, American College of Emergency Physicians
www.ohacep.org
CASE STUDY #4: BUTTON BATTERY INGESTION

1. Any patient presenting with possible foreign body ingestion should have a
complete assessment of his airway and respiratory status, including pulse
oximetry readings when indicated. The child should remain in the upright position
and NPO. Both anteroposterior and lateral radiographs should be obtained,
imaging from the nasopharynx to the anus to localize the position of the foreign
body.

2 Complications may occur for several reasons, including electrical discharge,
pressure necrosis, obstruction and leakage of battery contents. Electrical
discharge is the most important mechanism in most clinically significant cases.
Discharged batteries still retain enough voltage and storage capability to
generate an external current; however newer batteries are associated with a
greater potential for tissue damage. The larger the battery the more likely an
esophageal obstruction will occur. Esophageal perforation and aspiration have
also been reported. In the majority of cases, 89% in one series, the battery will
pass spontaneously without complication. Systemic absorption of heavy metals
from broken or fragmented batteries is a common concern but has been rarely
reported. Mercury batteries may pose a particular hazard if they break.

3 This battery requires emergent removal because of its location in the esophagus.
Esophageal injury from button batteries has been reported in less than two
hours. Endoscopy is the removal method of choice. Foley catheters have been
recommended for removal of esophageal foreign bodies, but their use carries
an added risk of aspiration. Magnetized probes are an alternative in skilled
hands.

Risks are lower after entry into stomach but not absent. For button batteries
in the stomach, monitoring of stool content or follow up x-ray in one week is
recommended. Parents should be educated about concerning symptoms,
including abdominal pain and vomiting.
[8]
© Ohio Chapter, American College of Emergency Physicians
www.ohacep.org